Engines produce mechanical power in which reciprocating motion of one or more pistons causes rotational motion of a crankshaft. The rotational energy of the crankshaft is transmitted to other devices, such as wheels of a vehicle. In addition, the rotational energy of the crankshaft can be transmitted to a gear (or belt) on the end of the crankshaft. The gear may be part of a gear train that transmits rotational energy to accessory features of the engine (e.g., to pumps, a camshaft, etc.). These types of gear trains often include one or more idler gears that allow the rotational direction and/or gear ratio of accessory gears in the gear train to be established as necessary. The idler gears may be mounted to an appropriate portion of the engine by a stub shaft.
An exemplary stub shaft is described in U.S. Patent Application Publication No. 2012/0298068, which published on Nov. 29, 2012 (“the '068 publication). The '068 publication describes an oil pump that includes a stub shaft for an idler gear. The stub shaft includes a fastener bore through which a threaded fastener extends to attach the stub shaft to a housing of the oil pump. An idler gear is connected to an end of the stub shaft, and lubricated by way of separately drilled passages in the stub shaft.
While the stub shaft of the '068 publication may be suitable for some applications, it may have some drawbacks. For example, the stub shaft of the '068 publication is secured at only one end, which may allow for flexing or movement of the stub shaft during use. Further, the stub shaft positions the idler gear against the pump housing, which may be unsuitable for other applications. In addition, the use of separately drilled passages within the stub shaft to supply oil to the idler gear may be undesirable for relatively narrow diameter stub shafts, in which space is limited.
The present disclosure is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.